A steady flow air compressor compresses 50 lb/min from 14 psia and 80 degrees F to a discharge state at 45 psia and 300 degrees F. Heat departs from the air only via circulating water that enters the jacket at 75 degrees F and leaves at 95 degrees F, circulating at the rate of 15lb/min. Let the frictional losses external to the fluid be 10% of the fluid work. Determine (a) the size of the driving motor required and (b) the rate of the change of entropy of the air.
Ans. (a) 76.5 hp (b) .1195 Btu/degreesR-min.
I'm not sure how to deal with the information given to me concerning the water. I think I use the equation: W=m(cp)(T2-T1). I have never done a compressor problem before so I'm scrambling. I would appreciate as much help as you can give me.
This solution demonstrates how to find the size of the driving motor and the rate of change of entropy of the air using various equations. The answer is provided in an attached .bmp file.